Auriophilicity in Polynuclear (Phosphane)gold(I) Thiolates {Me₃CS[Au(PPh₃)]₂}⁺ BF^‐₄ and {(CH₂S)₂[Au(PPh₃)]₃}⁺ BF^‐₄

The reaction of tert‐butanethiol with tris[(triphenylphosphane)gold(I)]oxonium tetrafluoroborate in dichloromethane in the presence of sodium tetrafluoroborate gave quantitative yields of a product {Me₃CS[Au(PPh₃)]₂}⁺ BF^‐₄ (1). In the crystal lattice of this salt, the sulfonium cations are associated into dimers through close Au…Au contacts. The centrosym‐metrical tetranuclear unit has Au…Au distances of 3.292(1) and 3.206(1) Å, and the Au‐S‐Au angles are exactly 90.0(1)°. Both data are indicative of significant intra‐ and intercationic Au…Au attractions. The analogous reaction of ethane‐1, 2–dithiol afforded high yields of a product {(CH₂S)₂[Au(PPh₃)]₃}⁺ BF^‐₄ (2). The compound is fluxional in CD₂Cl₂ solution and shows only one ³¹P‐NMR signal at ‐60°C. In the crystal, the quasi C₂‐symmetrical trinuclear cations feature the sulfur atoms in bridging positions between two gold atoms. The central gold atom is thus three‐coordinate; the peripheral gold atoms are two‐coordinate with Au…Au contacts at 3.284(1) and 3.129(1) Å and Au‐S‐Au angles as small as 86.5(1) and 81.0(1)°. This provides clear evidence for “auriophilic” bonding.